Behaviors: Traveling

Sperm whales can be found in all of the oceans in the world. They reside in water deeper than 3,000 ft, and avoid areas covered in ice. They are an extremely mobile species who have the ability to travel long distances at relatively fast speeds, however there is a notable difference in the travel range of adult males and female social groups.

Adult males live more solitary lives in cold water in the higher latitudes, and travel to more temperate or tropical water only during mating season. They can maintain cruising speeds between 3 to 9 mph (5 – 15 kph) for many hours, but have the ability to swim at a faster pace up to 25 mph (40 kph) for a shorter period if necessary. It is estimated that they can cover approximately 40 mi (64 km) per day, and as much as 15,000 mi (24,000 km) annually. Male sperm whales travel to follow food sources and for the purpose of breeding.

Females and social units reside in tropical and subtropical water, and regularly travel over a range of 600 – 900 miles. Movement patterns differ among sperm whale clans and are dependent upon the region where they live and the use of that habitat. Social units travel to locate food and if foraging is successful will remain in an area for several hours to days at a time. More vulnerable than the massive adult males, females and their social groups will move to avoid predators despite the availability of food.

We are more familiar with the traveling habits of the sperm whales who inhabit the Eastern Caribbean. The islands of the Lesser Antilles form an interconnected ecosystem spanning a range of about 285 mi (460 km), which provide plentiful resources for this relatively small and isolated population of whales.

The social units make use of the resources throughout the area, moving readily between islands at speeds of about 3 mph (4 -5 kph) whether they are cruising at the surface or foraging underwater. They are capable of swimming 30 miles (50 km) in a day, and can easily cover the distances between any of the five islands in a matter of days.

We typically see families from the larger of the two Eastern Caribbean clans along the coast of Dominica. Foraging strategies are culturally inherited among sperm whales and we believe that social units pass information specifying range preferences between generations. We therefore see certain social groups in this region more consistently than others.

Our observation period is limited to daylight hours and we find the whales as they make their way to or from the island, and when moving parallel to the coast performing various activities. It is speculated that they travel major distances between islands at night, however this is unsubstantiated.

We regularly observe individuals and social units in different modes of travel along the Dominican coastline. They may be swimming en route to a feeding location, relocating between sleep cycles or socialization periods, or swimming offshore to avoid predators. The whales swim as a group and may be loosely spread out, however they are always within auditory range of one another. Calves are accompanied by one or more adults who remain in closer proximity.

The pace of travel for social units is limited by the speed of their youngest members. To compensate for this potential liability, the whales have developed adaptive measures to increase the speed and endurance of their calves. When the groups travel long distances, adults swim in tandem with calves in a specific manner, often but not exclusively in mother-calf pairs.

As the pairs move in unison, each calf assumes a standard position with its rostrum tucked into the genital area of the adult. The curvature of the adult’s genital region forms a perfect groove for the calf’s nose to fit into, providing not only protection and comfort but also a hydrodynamic advantage as the calf is pulled along within the slipstream created by the larger and stronger adult. When the calves need to breathe, they slide out from under the adult to surface for a quick breath before resuming their traveling position.

We have been able to film several social units in various rhythms of traveling. We have documented them swimming solo, in pairs, and as groups in loose formation at slow, medium and rapid paces.